1. Field of the Invention
The present invention relates to a transport platform and, more particularly, to a transport platform for efficiently transmitting various cable broadcast services.
2. Discussion of the Related Art
Existing wired broadcast service that provides multi-channel video services to a subscriber chiefly uses a Hybrid Fiber Coax (hereinafter referred to as ‘HFC’)-based cable network as a transmission medium. The HFC network transfers an MPEG-2 TS-based broadcast stream through a modulated Radio Frequency (RF) signal from a headend, that is, the transport service supply point of a service provider, to the subscriber device of a home, performs optical transmission through the analog up-conversion of the modulated RF signal from the headend to the service entry point of a subscriber service group, and transmits the RF signal through photoelectric conversion from an Optical Network Unit (ONU), that is, the end point of optical transmission, to a subscriber.
In RF-based transmission service using the above method, not only MPEG-2 TS-based broadcast service, but also IP-based data transmission is provided through an MPEG-2 TS container according to a Data over Cable Service Interface Specification (IDOCSIS) standard. To this end, an expensive Cable Modem Termination System (CMTS) is necessary for the headend, and frequency bands are also inefficiently used because some frequency bands other than frequency bands for broadcast are shared by a service group and used as frequency bands for data transmission.
Furthermore, with the recent development of high-speed Time Division Multiplexing (TDM) optical transmission technology, such as an Ethernet Passive Optical Network (EPON) of a 1 Gbps band, a cheap Optical Line Terminal (OLT) can be configured. Furthermore, a bandwidth that can accommodate an optical transmission section is rapidly increased owing to technology, such as a 10G Passive Optical Network (PON) or wavelength-division multiplexing, but a bottleneck phenomenon is inevitable in using the frequency band in a coaxial cable section because of the sharing of a broadcast frequency band and high costs for cable data transmission.
Accordingly, an HFC network is evolving into a combination of a PON and cable broadcast, such as RF over Glass (RFoG), a DOCSIS-PON, and EPON over Cable (EPoC), technology in which a coaxial section is brought closer to a subscriber in order to increase the quality of a cable transmission signal, and technology in which RF/IP convergence transmission is efficiently accommodated, such as a Converged Cable Access Platform (CCAP). In the recent rapid trend of smart service development, broadcast-data convergence type transmission accompanied by IP-based data is also necessary even in the broadcast service. Accordingly, it is necessary to construct a transport platform for an improved frequency band and efficient RF/IP convergence type transmission in a cable network.